Renormalization-group mass suppression criterion (${\int }_0^t(\delta (g(u))-1)du\to -\infty$)

The effective dimensionless mass is $e^{-t}m(t)/\mu$. It vanishes precisely when this integrated exponent tends to minus infinity, for positive initial mass. An eventual bound $\delta \le 1-\eta$ is sufficient. Replacing the massive correlator by its massless limit additionally requires regularity uniform along the coupling trajectory.